Experimental Taxonomy Of Chaetomorpha And Its Epiphytic Algae

The green algal genus Chaetomorpha belongs to the family Cladophoraceae (Cladophorales). Its taxonomy is rather disputed because of the limited numbers of morphological characters and their plasticity varied by natural environment.This study was carried out to investigate the experimental taxonomy of Chaetomorpha samples. Two target samples collected from Rongcheng city, China were chosen and characterized on the basis of experimental biology characters. Based on the unialgal culture, their life cycles and developmental morphological characters were observed microscopically. Suitable temperature and light intensity for growth and reproduction in different stages of life cycle were examined over a wide range of light and temperature regimes. Morphological characters, developmental morphologies and ecological habits were compared between the two samples. Four characters from experimental biology, viz. monoecious or dioecious gametangium, branch or not, size of reproductive cell and type of basal holdfast were considered as distinguished criteria to classify morphologically similar samples.Following these criteria, with combination of morphological characters, we propose sample 1 and 2 are treated as different species although they are obviously same according to morphological identification.According to the experimental data of suitable temperature range, we analyzed probable biogeographical distribution region of target Chaetomorpha and presumed its potential possibility of southward invasion along China coast.During laboratory culture of Chaetomorpha samples, two epiphytic components of microphytic chlorophyte were encouraged. With above mentioned experimental taxonomy method, their morphological examination and isolated culture experiments were carried out. In comparison of experimental biology and morphological characters, they were identified respectively as a species of Gongrosira (Chaetophoraceae, Chlorophyta) and as a new record, Acrochaete leptochaete (Chaetophoraceae, Chlorophyta) in China territorial waters. Their morphology, taxonomy and distribution were discussed in details as well.These results indicate that experimental taxonomy is a beneficial supplementary to morphology. As one of supplementary identification approach, this way merging into morphological taxonomy will become more significant to increase the accuracy of traditional taxonomy.